To address health disparities and inappropriate service use experienced by individuals with serious mental illness, there is a critical need to evaluate approaches that integrate primary care within specialty mental health settings to improve care access and health outcomes. Numerous studies have shown the benefits of integrated care. However, only limited research demonstrates the best approaches and settings to integrate health services for the seriously mentally ill. The long-term goal is to understand how health care integration for the seriously mentally ill can improve quality of care and health outcomes. The overall objective is to examine service use and quality of care before and after the introduction of a Health Home Initiative. Using longitudinal administrative data from both the Health Home Initiative and the Medicaid program, integration strategies implemented in community mental health centers that employed diverse care delivery models (coordinated, colocated, integrated) can be compared. The central hypothesis is that the Health Home Initiative alone, and in consort with an integrated care delivery model, can increase access to outpatient services, decrease potentially avoidable service use and improve quality of care. Findings from efficacy trials and expert opinion support this hypothesis. The rationale for the proposed research is that understanding the study outcomes will inform and guide policymakers as well as states implementing similar initiatives. The central hypothesis will be tested by pursing the following two aims: 1) Determine the extent to which Health Homes impacted service use and quality of care; and 2) Identify how care model setting affected service use and quality of care for Health Home participants. To complete these aims innovative analytic methods will be used to conduct a quasi- experimental research design, which allows for causal inferences. Propensity score matching will be used to achieve conditional exchangeability between the treatment and control populations; and a difference-in- differences analysis to control for confounding trends attributed to exogenous events that may obscure true effects. The proposed research will contribute to the understanding of approaches that integrate primary care into community mental health settings. This contribution will be significant as it is expected to provide evidence that can guide policy development and treatment decisions for health care systems and providers working with a heavily disenfranchised patient population. Completion of the aims will not only help to determine the impact of Health Homes on service use and quality of care, but identify the care setting (i.e. coordination, colocation, or integrated) most amenable to integration strategies. Moreover, the Health Home Initiative, which took place in a real-world setting, allows our findings to be more relevant than those from efficacy trials for healthcare decision making by providers and policymakers.